1. Field of the Invention
The present invention relates generally to earth anchors, and more particularly, to a cast screw anchor which is of lighter weight and equal strength to previous cast anchors, and may be installed with less torque to a greater depth in dense or frozen soils than has heretofore been the case.
2. Description of the Prior Art
U.S. Pat. No. 4,981,000, assigned to the assignee hereof, illustrates and describes a cast anchor which provided for improved penetration in frozen, stony or dense soils. Although the cast anchor of the '000 patent was an improvement over other previously available screw anchors, such as those shown in the assignee's U.S. Pat. Nos. 4,334,392 and 4,467,575 for the reasons explained in the '000 patent, it was found that under certain difficult soil conditions, the torque required to install the cast anchors was greater than desirable, and the anchor could not be installed to a requisite depth without exceeding the torque capacity available.